In this study, we expand on the examination of genetically determined differences in host responses that correlate with clearance of Chlamydia trachomatis from the genital tract. We infected C57BL/6, BALB/c, and C3H/HeN mice with the mouse pneumonitis agent of C. trachomatis (MoPn). C57BL/6 mice had the shortest course of infection (22 days) and the lowest incidence of severe hydrosalpinx. BALB/c mice also had a short course of infection (25 days), but all developed hydrosalpinx. C3H/HeN mice had the longest course of infection (38 days), and all developed severe hydrosalpinx. Determination of local cytokine responses by enzyme-linked immunosorbent assay (ELISA) of genital tract secretions revealed that the levels of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-␣) and interleukin-1␤ (IL-1␤) were significantly increased in the C57BL/6 and BALB/c strains compared to those in the C3H/HeN strain whereas the level of IL-6 was not different. The level of the neutrophil chemokine macrophage inflammatory protein 2 (MIP-2) was increased during the first week of infection in all three strains but was significantly higher in the BALB/c strain, the strain with the most rapid influx of neutrophils into the genital tract. Prolonged detection of MIP-2 in C3H/HeN mice was associated with a protracted presence of neutrophils in the genital tract. Early increases in the levels of the proinflammatory cytokines TNF-␣ and IL-1␤ are associated with earlier eradication of infection in the C57BL/6 and BALB/c strains than in the C3H/HeN strain. Increased levels of MIP-2 and neutrophils in BALB/c and C3H/HeN mice relative to C57BL/6 mice suggest that these responses may contribute to pathology.

Vaginal infection with the mouse pneumonitis agent of Chlamydia trachomatis (MoPn) produces shorter courses of infection in C57BL/6 and BALB/c mice than in C3H/HeN mice, while C57BL/6 mice are more resistant to oviduct pathology. A robust Th1 response is extremely important in host defense against chlamydia. In this study we examined gamma interferon (IFN-␥), interleukin 10 (IL-10), and the T-cell-regulatory chemokines macrophage inflammatory protein-1␣ (MIP-1␣) and monocyte chemoattractant protein-1 (MCP-1) to determine if differences in these responses were associated with the differential courses of infection seen in these three strains of mice. Increased and prolonged IFN-␥ responses and lower IL-10 responses were observed in the C57BL/6 strain compared to BALB/c and C3H. Examination of genital tract chemokines revealed a marked predominance of MIP-1␣ over MCP-1 only in the C57 strain. Thus, a pattern of high MIP-1␣ and low MCP-1 levels during the first week of infection is associated with an increased Th1 response and a shorter, more benign chlamydial infection. Inhibition of the MCP-1 response in C3H mice increased their later T-cell production of IFN-␥ but decreased their early IFN-␥ response and had no effect on the course or outcome of infection. Inhibition of MCP-1 is not beneficial in chlamydial infection because of its pleiotropic effects.A key issue for the study of chlamydial infection is to understand why individuals infected with Chlamydia trachomatis experience different clinical outcomes. Cytokine patterns elicited by infection are critical in the regulation of the adaptive immune response and in the resolution of infection. We used a mouse model of ascending chlamydial genital tract infection to explore genetically controlled differences in the host response that lead to differential outcomes of chlamydial infection. Vaginal infection of C57BL/6 (C57), BALB/c, and C3H/ HeN (C3H) mice with the mouse pneumonitis biovar of C. trachomatis (MoPn) results in genital tract infections that differ with respect to duration and outcome (5,6,8). The C57 strain exhibits a short duration of infection and the least oviduct pathology. The BALB/c strain also exhibits an infection of relatively short duration, but despite this, the mice develop severe oviduct pathology. The C3H strain exhibits a longer course of infection and also develops severe oviduct pathology (5,6,8). Thus, the C57 strain exhibits the least susceptible phenotype, the BALB/c strain exhibits an intermediate phenotype, and the C3H strain exhibits the most susceptible pheno-

Case reports have been vital to the advancement of medicine, providing a mechanism for scholarly education and for sharing new discovery and rare observations. However, journals are increasingly reluctant to publish this type of manuscript. Additionally, case reports and limited case series are infrequently cited, potentially interfering with the impact factor of a journal. The increasing emphasis on evidence-based medicine may have artificially decreased the value of case reports. This article describes the value of case reports to medicine, citing 3 examples that have significantly improved the practice of medicine. We also provide criteria for effective reporting, which include the elements of both surprise and closure. In summary, we offer support for the contention that case reports are fundamental to the scholarly practice of medicine and enhance the intent of a quality medical journal.

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